單片機(jī)控制DAC0832產(chǎn)生各種波形，實(shí)質(zhì)就是單片機(jī)把波形的采樣點(diǎn)數(shù)據(jù)送至DAC0832,經(jīng)D/A轉(zhuǎn)換后輸出模擬信號。改變送出的函數(shù)波形采樣點(diǎn)后的延時時間，就可改變函數(shù)波形的頻率。產(chǎn)生各種函數(shù)波形的原理如下。
(1)正弦波產(chǎn)生原理。單片機(jī)把正弦波的256個采樣點(diǎn)的數(shù)據(jù)送給DAC0832。正弦波采樣數(shù)據(jù)可采用軟件編程或MATLAB等工具計(jì)算。
(2)方波產(chǎn)生原理。方波只有高、低電平的兩個采樣點(diǎn)的數(shù)據(jù)。單片機(jī)采用定時器定時中斷，時間常數(shù)決定方波高、低電平的持續(xù)時間。
#include<reg51.h>
sbit wr=P3^6;
sbit rd=P3^2;
sbit key0=P1^0; //定義P1.0腳的按鍵為正弦波鍵key0
sbit key1=P1^1; //定義P1.1腳的按鍵為方波鍵key1
sbit key2=P1^2; //定義P1.2腳的按鍵為三角波鍵key2
unsigned char flag; //flag為1、2、3是對應(yīng)的正弦波、方波、三角波
unsigned char const code //為正弦波采樣點(diǎn)數(shù)組的256個數(shù)據(jù)
SIN_code[256]={0x80,0x83,0x86,0x89,0x8c,0x8f,0x92,0x95,0x98,0x9c,0x9f,0xa2,
0xa5,0xa8,0xab,0xae,0xb0,0xb3,0xb6,0xb9,0xbc,0xbf,0xc1,0xc4,0xc7,0xc9,0xcc,0xce,
0xd1,0xd3,0xd5,0xd8,0xda,0xdc,0xde,0xe0,0xe2,0xe4,0xe6,0xe8,0xea,0xec,0xed,0xef,
0xf0,0xf2,0xf3,0xf4,0xf6,0xf7,0xf8,0xf9,0xfa,0xfb,0xfc,0xfc,0xfd,0xfe,0xfe,0xff,
0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xfe,0xfe,0xfd,0xfc,0xfc,0xfb,
0xfa,0xf9,0xf8,0xf7,0xf6,0xf5,0xf3,0xf2,0xf0,0xef,0xed,0xec,0xea,0xe8,0xe6,0xe4,
0xe3,0xe1,0xde,0xdc,0xda,0xd8,0xd6,0xd3,0xd1,0xce,0xcc,0xc9,0xc7,0xc4,0xc1,0xbf,
0xbc,0xb9,0xb6,0xb4,0xb1,0xae,0xab,0xa8,0xa5,0xa2,0x9f,0x9c,0x99,0x96,0x92,0x8f,
0x8c,0x89,0x86,0x83,0x80,0x7d,0x79,0x76,0x73,0x70,0x6d,0x6a,0x67,0x64,0x61,
0x5e,0x5b,0x58,0x55,0x52,0x4f,0x4c,0x49,0x46,0x43,0x41,0x3e,0x3b,0x39,0x36,
0x33,0x31,0x2e,0x2c,0x2a,0x27,0x25,0x23,0x21,0x1f,0x1d,0x1b,0x19,0x17,0x15,
0x14,0x12,0x10,0xf,0xd,0xc,0xb,0x9,0x8,0x7,0x6,0x5,0x4,0x3,0x3,0x2,0x1,0x1,0x0,
0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x1,0x1,0x2,0x3,0x3,0x4,0x5,0x6,0x7,
0x8,0x9,0xa,0xc,0xd,0xe,0x10,0x12,0x13,0x15,0x17,0x18,0x1a,0x1c,0x1e,0x20,0x23,
0x25,0x27,0x29,0x2c,0x2e,0x30,0x33,0x35,0x38,0x3b,0x3d,0x40,0x43,0x46,0x48,
0x4b,0x4e,0x51,0x54,0x57,0x5a,0x5d,0x60,0x63,0x66,0x69,0x6c,0x6f,0x73,0x76,0x79,0x7c};
unsigned char keyscan() //鍵盤掃描函數(shù)
{
unsigned char keyscan_num,temp;
P1=0xff; //P1口輸入
temp=P1; //從P1口讀入鍵值，存入temp中
if(~(temp&0xff)) //判斷是否有鍵按下，即鍵值不為0xff，則有鍵按下
{
if(key0==0) //產(chǎn)生正弦波的按鍵按下，P1.0=0
{
P0=0xf9; //數(shù)碼管顯示1
keyscan_num=1; //得到的鍵值為1，表示產(chǎn)生正弦波
}
else if(key1==0) //產(chǎn)生方波的按鍵按下，P1.1=0
{
P0=0xa4; //數(shù)碼管顯示2
keyscan_num=2; //得到的鍵值為2，表示產(chǎn)生方波
}
else if(key2==0) //產(chǎn)生三角波的按鍵按下，P1.2=0
{
P0=0xb0; //數(shù)碼管顯示3
keyscan_num=3; //得到的鍵值為3，表示產(chǎn)生三角波
}
else
{
keyscan_num=0; //沒有按鍵按下，鍵值為0
}
return keyscan_num; //得到的鍵值返回
}
}
void init_DAC0832() //DAC0832初始化函數(shù)
{
rd=0;
wr=0;
}
void SIN() //正弦函數(shù)
{
unsigned int i;
do{
P2=SIN_code[ i]; //由P2口輸出給DAC0832正弦波數(shù)據(jù)
i=i+1; //數(shù)組數(shù)據(jù)指針加1
}while(i<256); //判斷是否已輸出完256個波形數(shù)據(jù)，未完就繼續(xù)輸出數(shù)據(jù)
}
void Square() //方波函數(shù)
{
EA=1; //總中斷允許
ET0=1; //允許T0中斷
TMOD=1; //T0工作在方式1
TH0=0xff; //給T0高8位裝入時間常數(shù)
TL0=0x83; //給T0低8位裝入時間常數(shù)
TR0=1; //啟動T0
}
..........
QQ好友和群
QQ空間
騰訊微博
騰訊朋友
收藏
淘帖
頂
踩
